fix(cloudflare): Convert MX name from @ to root domain

- https://git.selfprivacy.org/SelfPrivacy/selfprivacy.org.app/issues/265

lib/logic/cubit/server_installation/server_installation_cubit.dart

@@ -270,6 +270,7 @@ class ServerInstallationCubit extends Cubit<ServerInstallationState> {
       records: getProjectDnsRecords(
         state.serverDomain!.domainName,
         serverDetails.ip4,
+        false,
       ),
       domain: state.serverDomain!,
     );
@@ -277,6 +278,7 @@ class ServerInstallationCubit extends Cubit<ServerInstallationState> {
       records: getProjectDnsRecords(
         state.serverDomain!.domainName,
         serverDetails.ip4,
+        true,
       ),
       domain: state.serverDomain!,
     );

lib/logic/models/json/dns_providers/cloudflare_dns_adapter.dart

@@ -4,14 +4,18 @@ CloudflareDnsRecord _fromDnsRecord(
   final DnsRecord dnsRecord,
   final String rootDomain,
 ) {
+  final String type = dnsRecord.type;
   String name = dnsRecord.name ?? '';
   if (name != rootDomain && name != '@') {
     name = '$name.$rootDomain';
   }
+  if (type == 'MX' && name == '@') {
+    name = rootDomain;
+  }
   return CloudflareDnsRecord(
     content: dnsRecord.content,
     name: name,
-    type: dnsRecord.type,
+    type: type,
     zoneName: rootDomain,
     id: null,
     ttl: dnsRecord.ttl,

lib/utils/network_utils.dart

@@ -93,6 +93,7 @@ void launchURL(final url) async {
 List<DnsRecord> getProjectDnsRecords(
   final String? domainName,
   final String? ip4,
+  final bool isCreating,
 ) {
   final DnsRecord domainA =
       DnsRecord(type: 'A', name: domainName, content: ip4);
@@ -139,7 +140,7 @@ List<DnsRecord> getProjectDnsRecords(
     mx,
     txt1,
     txt2,
-    txt3,
+    if (!isCreating) txt3,
     vpn,
   ];
 }